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<html>

<head>
  <meta charset='utf-8'>
  <meta name='viewport' content='width=device-width, initial-scale=1, user-scalable=no'>
  <meta name='mobile-web-app-capable' content='yes'>
  <meta name='apple-mobile-web-app-capable' content='yes'>
  <link rel='icon' type='image/png' sizes='32x32' href='../favicon-32x32.png'>
  <link rel='icon' type='image/png' sizes='96x96' href='../favicon-96x96.png'>
  <link rel='stylesheet' href='../css/common.css'>

  <title>Equirect Layer</title>
  <!-- Stereo layer dependency -->
  <script src="../js/wglu/wglu-program.js"></script>
  <script src="../js/wglu/wglu-url.js"></script>
  <script src="../js/stereo-util.js"></script>
</head>

<body>
  <header style="max-width: 800px;">
    <details open>
      <summary>Equirect Video</summary>
      <p>
        This sample shows how to show 180/360 video via an equirect layer, with
        the addition of media control bar that enables fast forward/rewind,
        pause/play and exit. It can be used for rendering static backgrounds like cube
        layers, as demonstrated in the Equirect Layer example, but the real edge
        of using equirect layers over cube layers is to show immersive video.
      </p>
      <p>
        NOTE: Depending on your internet connection, the fast forward and rewind
        buttons may not immediately take effect.
      </p>
        <a class="back" href="./index.html">Back</a>
      </p>
      <!-- Hide video selection drop down until more videos are available -->
      <label style="visibility: hidden;">Choose a video</label>
      <select id="eqrtVideoSelect" style="visibility: hidden;">
        <option value="https://d25a56pc18k0co.cloudfront.net/sloths_binaural_3840_180_3D-injected.mp4"
          data-video-width=3840 data-video-height=1920 data-video-layout="stereo-left-right" data-video-angle=180 data-video-fps=30>
          stereo-left-right 180 3840x1920 30fps
        </option>
      </select><br />
    </details>
  </header>
  <main style='text-align: center;'>
    <p>Click 'Enter VR' to see content</p>
  </main>
  <script type="module">
    import { WebXRButton } from '../js/util/webxr-button.js';
    import { Scene, WebXRView } from '../js/render/scenes/scene.js';
    import { Renderer, createWebGLContext } from '../js/render/core/renderer.js';
    import { QueryArgs } from '../js/util/query-args.js';
    import { MenuSystem } from '../js/render/nodes/menu-system.js';

    // If requested, use the polyfill to provide support for mobile devices
    // and devices which only support WebVR.
    import WebXRPolyfill from '../js/third-party/webxr-polyfill/build/webxr-polyfill.module.js';
    if (QueryArgs.getBool('usePolyfill', true)) {
      let polyfill = new WebXRPolyfill();
    }

    // XR globals.
    let xrButton = null;
    let xrSession = null;
    let xrRefSpace = null;
    let xrGLFactory = null;
    let xrFramebuffer = null;
    let stereoUtil = null;

    // WebGL scene globals.
    let gl = null;
    let renderer = null;
    let scene = new Scene();

    // Layer globals
    let projLayer = null;
    let eqrtLayer = null;
    let eqrtVideoElement = null;
    let eqrtVideoWidth = 0;
    let eqrtVideoHeight = 0;
    let eqrtVideoNeedsUpdate = false;

    // Set up media control bar
    let menuSystem = new MenuSystem();
    menuSystem.createButton('../media/textures/backward-button.png', () => { eqrtVideoElement.currentTime -= 15; });
    menuSystem.createSwitch(
      '../media/textures/pause-button.png', () => eqrtVideoElement.pause(),
      '../media/textures/play-button.png', () => eqrtVideoElement.play()
    );
    menuSystem.createButton('../media/textures/forward-button.png', () => { eqrtVideoElement.currentTime += 15; });
    menuSystem.createButton('../media/textures/x-button.png', () => { xrSession.end() });
    scene.addNode(menuSystem.getMenuBarNode());

    function initXR() {
      xrButton = new WebXRButton({
        onRequestSession: onRequestSession,
        onEndSession: onEndSession
      });
      document.querySelector('header').appendChild(xrButton.domElement);

      if (navigator.xr) {
        navigator.xr.isSessionSupported('immersive-vr').then((supported) => {
          xrButton.enabled = supported;
        });
      }
    }

    function onRequestSession() {
      if (!xrSession) {
        navigator.xr.requestSession('immersive-vr', {
          requiredFeatures: ['layers'],
        }).then(onSessionStarted);
      } else {
        onEndSession();
      }
    }

    function initGL() {
      if (gl) { return; }
      gl = createWebGLContext({ xrCompatible: true, webgl2: true, });
      document.body.appendChild(gl.canvas);
      gl.clearColor(0.0, 0, 0, 0.0);

      function onResize() {
        gl.canvas.width = gl.canvas.clientWidth * window.devicePixelRatio;
        gl.canvas.height = gl.canvas.clientHeight * window.devicePixelRatio;
      }
      window.addEventListener('resize', onResize);
      onResize();

      renderer = new Renderer(gl);
      scene.setRenderer(renderer);

      // Util for rendering stereo layers
      stereoUtil = new VRStereoUtil(gl);
    }

    function onSessionStarted(session) {
      xrSession = session;
      scene.inputRenderer.useProfileControllerMeshes(session);
      session.addEventListener('end', onSessionEnded);

      initGL();

      xrFramebuffer = gl.createFramebuffer();
      xrGLFactory = new XRWebGLBinding(session, gl);

      let selected = document.getElementById("eqrtVideoSelect");
      eqrtVideoElement = document.createElement('video');
      eqrtVideoElement.loop = true;
      eqrtVideoElement.crossOrigin = "anonymous";
      eqrtVideoElement.preload = 'auto';
      eqrtVideoElement.autoload = true;
      eqrtVideoElement.src = selected.options[selected.selectedIndex].value;
      eqrtVideoWidth = selected.options[selected.selectedIndex].getAttribute("data-video-width");
      eqrtVideoHeight = selected.options[selected.selectedIndex].getAttribute("data-video-height");
      let eqrtVideoAngle = selected.options[selected.selectedIndex].getAttribute("data-video-angle");
      let eqrtVideoLayout = selected.options[selected.selectedIndex].getAttribute("data-video-layout");
      let eqrtRadius = 10;
      let eqrtVideoFPS = selected.options[selected.selectedIndex].getAttribute("data-video-fps");


      eqrtVideoElement.play();
      setInterval(function () {
        if (eqrtVideoElement.readyState >= eqrtVideoElement.HAVE_CURRENT_DATA) {
          eqrtVideoNeedsUpdate = true;
        }
      }, 1000 / eqrtVideoFPS);

      session.requestReferenceSpace('local').then((refSpace) => {
        xrRefSpace = refSpace;
        projLayer = xrGLFactory.createProjectionLayer({ space: refSpace, stencil: false });
        eqrtLayer = xrGLFactory.createEquirectLayer({
          space: refSpace,
          viewPixelWidth: eqrtVideoWidth / (eqrtVideoLayout === "stereo-left-right" ? 2 : 1),
          viewPixelHeight: eqrtVideoHeight / (eqrtVideoLayout === "stereo-top-bottom" ? 2 : 1),
          layout: eqrtVideoLayout,
        });

        eqrtLayer.centralHorizontalAngle = Math.PI * eqrtVideoAngle / 180;
        eqrtLayer.upperVerticalAngle = Math.PI / 2.0;
        eqrtLayer.lowerVerticalAngle = -Math.PI / 2.0;
        eqrtLayer.radius = eqrtRadius;
        session.updateRenderState({ layers: [eqrtLayer, projLayer] });

        session.requestAnimationFrame(onXRFrame);
      });
    }

    function onEndSession() {
      xrSession.end();
    }

    function onSessionEnded(event) {
      if (event.session.isImmersive) {
        xrButton.setSession(null);
      }
      xrSession = null;
      eqrtVideoElement.pause();
      gl = null;
    }

    function buttonPressedThisFrame(gamepad, index) {
      return (index < gamepad.buttons.length &&
        gamepad.buttons[index].pressed);
    }

    function onXRFrame(time, frame) {
      let pose = frame.getViewerPose(xrRefSpace);
      xrSession.requestAnimationFrame(onXRFrame);

      if (eqrtLayer && (eqrtVideoNeedsUpdate || eqrtLayer.needsRedraw)) {
        eqrtVideoNeedsUpdate = false;
        let glayer = xrGLFactory.getSubImage(eqrtLayer, frame);

        // TEXTURE_CUBE_MAP expects the Y to be flipped for the faces and it already
        // is flipped in our texture image.
        gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
        gl.bindTexture(gl.TEXTURE_2D, glayer.colorTexture);
        gl.texSubImage2D(gl.TEXTURE_2D, 0, 0, 0, eqrtVideoWidth, eqrtVideoHeight, gl.RGBA, gl.UNSIGNED_BYTE, eqrtVideoElement);
        gl.bindTexture(gl.TEXTURE_2D, null);
      }

      let force_mono = false;
      for (let source of xrSession.inputSources) {
        force_mono |= buttonPressedThisFrame(source.gamepad, 4);
      }
      eqrtLayer.forceMonoPresentation = force_mono;

      if (pose) {
        gl.bindFramebuffer(gl.FRAMEBUFFER, xrFramebuffer);
        // We need to invalidate the color (and depth, just in case) here to avoid
        // loading from the previously bound color texture. It will save some GPU time.
        gl.invalidateFramebuffer(gl.FRAMEBUFFER, [gl.COLOR_ATTACHMENT0, gl.DEPTH_ATTACHMENT]);

        scene.updateInputSources(frame, xrRefSpace);
        menuSystem.processInput(frame, scene, xrRefSpace);

        let views = [];
        for (let view of pose.views) {
          let viewport = null;
          let glLayer = xrGLFactory.getViewSubImage(projLayer, view);
          glLayer.framebuffer = xrFramebuffer;
          viewport = glLayer.viewport;
          gl.bindFramebuffer(gl.FRAMEBUFFER, xrFramebuffer);
          gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, glLayer.colorTexture, 0);
          gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.TEXTURE_2D, glLayer.depthStencilTexture, 0);
          views.push(new WebXRView(view, glLayer, viewport));
        }
        scene.drawViewArray(views);
      }
      scene.endFrame();
    }

    initXR();
  </script>
</body>

</html>
